I recently heard a sermon about not liking but loving! That is what sums it up for me, I don't like SSPX but I love SSPX followers because they all sound like sedevacantists to me, at least the ones here on this forum that are honest about Francis and his ilk.
Its really hard to take Pope Francis seriously, but Sedevacantism honestly entails a lot more than just never listening to Francis.
In practice it usually means
1: That the vast majority of priests in the world are not true priests
2: That every diocese in the world is vacant of authority.
3: A view of papal infallibility that is pretty close to unlimited.
4: Often refusing to commune with Catholics who make choices you don't like whether going to certain chapels or taking certain theological opinions (and I don't mean ones that were already condemned by the pre V2 Church here. I mean opinions on disputed questions like R and R, infallibility of canonizations, attendance at FSSP, SSPX, SSPV, or whatever, etc.
If the assertion was just "Francis isn't Pope", I wouldn't really care except for the fact that I'd feel hesitant to make that call. I'm comfortable praying for him as Pope and obeying any command that doesn't go against well informed conscience, even if there are precious few or even none that I actually can obey, unless or until the Church tells me this guy has no authority.
All that said, practically speaking, while I'd obey if Pope Francis gave a command like "we need to fast on Wednesdays and Fridays like the early church did", I practically ignore all that he teaches, so I guess some might compare that to a type of Sedeprivationism. But then, I theoretically think Pope Francis could teach something that met all the ex cathedra criteria, and I believe the Holy Ghost would protect him from error in that exact situation, even striking him dead if he had to. I guess a Sedeprivationist wouldn't think that.